Supply vessel

ABSTRACT

A supply vessel ( 6 ) equipped with passenger seating ( 21 ) for transferring service personnel to and from an offshore facility ( 1 ), said supply vessel having a transfer speed of at least 16 knots, wherein an aft deck of the supply vessel ( 6 ) has a tug boat layout equipped with at least one towing winch ( 11 ), and a tugger winch ( 12 ).

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority based on Danish Patent Application No. PA 2012 70745 filed on Nov. 30, 2012, the contents of all of which are incorporated herein by reference in their entirety.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable.

REFERENCE TO A MICROFICHE APPENDIX

Not Applicable.

BACKGROUND OF THE INVENTION

The present invention relates to a supply vessel equipped with passenger seating for transferring service personnel to and from an off-shore facility, said supply vessel having a transfer speed of at least 16 knots.

Supply vessels of this kind are used for transferring personnel from shore to an offshore facility, and from this facility back on shore. Some offshore facilities are unmanned and require service at intervals, such as three to four times per year. When repairs are to be performed, equipment needs to be sailed out to the offshore facility.

Offshore facilities also need to be installed, and during the construction phase there is need both for personnel and for equipment.

Different types of vessels are utilized at offshore facilities. Fast supply vessels are used for transferring personnel. These crew vessels are fast and carry only little weight. Other types of vessels are barges used for transferring equipment to the offshore facility. Barges are towed by tugs. Tugs are slow, but capable of exerting large pull in hawsers. There may also be a need for crane vessels, which are also slow and powerful.

An example of an offshore facility is an offshore wind farm, in which typically a large number of wind turbines are installed. The wind turbines are unmanned, but require service several times per year. Wind farms may be located at a considerable distance from shore, and the distance to the nearest port may be even larger.

BRIEF SUMMARY OF THE INVENTION

The considerable distance between the offshore facility and the shore results has as a result that it takes time to transfer personnel to and from the offshore facility, hence the need for fast vessels for transporting passengers between shore and the facility.

The present invention aims at facilitating the processes required at an offshore facility.

With an aim to this the supply vessel according to the present invention has an aft deck with a tug boat layout equipped with at least one towing winch, a stern roller, hydraulic pins, and a tugger winch.

With this design the supply vessel is capable of transferring personnel quickly to the offshore facility, and at the same time the supply vessel can perform as a tug and control one end of a barge used for transferring equipment or handle an anchor in order to position the barge at the offshore facility. It is thus possible to spare the use of one traditional tug and instead use the supply vessel of the present invention.

The supply vessel according to the present invention may have a transfer speed of at least 18 knots (nautical miles per hour), which allows for faster transfer than 16 knots. The supply vessel may even have a transfer speed of at least 20 knots. The higher speeds are preferred when the offshore facility is located more distant from the nearest port. In an embodiment the supply vessel has a transfer speed of at least 24 knots.

Preferably the towing winch has a pulling capacity of at least 20 t, and preferably a breaking capacity of at least 30 t. It is possible to use a towing winch of less capacity than 20 t. However, it is an advantage when the towing winch is more powerful, such as having a pulling capacity of at least 30 t, and a breaking capacity of at least 50 t. The pulling capacity is also called the bollard pull.

Preferably the tugger winch has a pulling capacity of at least 2 t. It is possible to use a tugger winch of less capacity than 2 t. However, it is an advantage when the tugger winch is more powerful, such as having a pulling capacity of at least 3 t.

In an embodiment, the aft deck of the supply vessel is equipped with a crane, which crane preferably is capable of lifting at least 4 t. Cranes of smaller size may also be used, or larger cranes such as a deck crane having a lifting capacity of at least 5 t.

It is possible to arrange seating for passengers in an outside area, such as on deck, but preferably the supply vessel has a deckhouse arranged with seating for at least 5 passengers. The transfer to the off-shore facility may take place in rough weather, and then it is an advantage to seat the passengers sheltered within the deckhouse. For some offshore sites it is an advantage if the supply vessel can transfer more persons per voyage, so in a preferred embodiment the deckhouse is arranged with seating for at least 10 passengers.

The bridge (may also be named wheelhouse or steering house) may be provided in a separate superstructure, however in an embodiment the deckhouse has a bridge located in the upper part of the deckhouse, which bridge is arranged with an aft maneuvering position. In this embodiment the towing winch, the hydraulic pins and the tugger winch are controllable from the aft maneuvering position. This provides a compact design, and thus a lower deadweight of the supply vessel, which is an advantage with respect to sailing with a high transfer speed.

In an embodiment the supply vessel has two hull sections arranged in parallel and spaced apart by a deck structure. The hull design is of catamaran type, but may alternatively be a single hull with twin-skegs, or may be a single hull and provided with more powerful engines.

In an embodiment the supply vessel is provided in its bow area with a fixed fender, such as a fender of rubber. Such a fender makes it possible to land personnel onto the offshore facility by sailing the fender on the bow into contact with the landing platform and holding the fender against the landing platform while the persons enter or leave the vessel, as the supply vessel pushes the fender against the offshore facility by use of the propulsion system. In this manner use of moorings can be reduced or avoided during the transfer of personnel. This is in particular an advantage if the sea state is high, and the supply vessel is moved by the sea in the vertical direction in relation to the stationary offshore facility.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

In the following examples of the supply vessel according to the present invention are described in more detail with reference to the illustrative drawings, on which

FIG. 1 illustrates a barge handled at an offshore facility,

FIG. 2 illustrates the supply vessel during transfer between an offshore site and a port site on shore,

FIGS. 3 and 4 illustrate an outline of a first embodiment of the supply vessel seen from above at deck level in FIG. 3, and in side view at the middle of the vessel in FIG. 4,

FIGS. 5 to 7 depict an outline of a second embodiment of the supply vessel seen in side view, in front view and in aft view, and

FIGS. 8 and 9 depict the second embodiment in views from the above of the lower deck area and the main deck area.

DETAILED DESCRIPTION OF THE INVENTION

An offshore facility 1 is located at a distance, such as 50 nautical miles (typically at least 25 nautical miles), from a shore location 7, such as a port. The offshore facility 1 can be a wind turbine in a wind turbine farm, a wave induced power generator, or any kind of offshore equipment or installation requiring periodic service or maintenance and possibly also use of equipment, such as a crane, located on a barge 4.

An offshore wind turbine is an unmanned offshore facility, which is either stationary by mounting on to or into the sea bed (via a foundation pile), or a floating construction held in position by anchoring or tension wires. The supply vessel 6 according to the present invention is in particular useful when equipment or parts are needed in connection with the work to be performed by the personnel at the offshore facility. When the equipment or parts are heavy they are not transported on the supply vessel itself. Heavy or bulky equipment or parts are typically transported to the offshore facility by a barge. The barge is hauled or pushed by a tug at slow speed, less than 10 knots, especially when the barge is loaded.

The offshore facility 1 is typically provided with a landing platform 2 onto which personnel and equipment are transferred or placed when service or repair of the turbine is required. Service and maintenance is typically scheduled, such as with two, three, four or six months interval in order to inspect, service, and when required repair the wind turbine. An offshore wind turbine may be provided with supervisory control and data acquisition systems, which monitor operation parameters of the wind turbine and sensors of various kinds. Based on the acquired data, a condition based preventive maintenance can be performed. Both the scheduled maintenance and the preventive maintenance are performed before an actual failure occurs, stopping the power production. If a failure occurs and stops power production, a corrective maintenance is required in order to repair the failure. Such corrective maintenance is expensive, because it is unplanned and the loss of production adds to the costs of maintenance and repair. Maintenance may thus be planned in a manner minimizing corrective maintenance. The number of service occasions per year may vary with the age of the offshore facility and with the data acquired from operation monitoring.

An individual service occasion involves at least transfer of service personnel from shore to the offshore facility 1 and back again, as indicated by arrow A in FIG. 2. The service occasion can also involve transfer of parts or equipment on barge 3.

Barge 3 holds parts to be used at the offshore facility, or is provided with equipment used for construction or repair of the site. The barge has been towed out to the offshore facility by a tug 4 connected to the barge by a hawser 5. At the offshore site the barge needs positioning, a job traditionally requiring two tugs. However, the supply vessel 6 of the present invention can control one end of the barge via a hawser 5, or the supply vessel can be utilized to handle anchors for anchoring the barge. The barge may be a simple barge holding parts and equipment, or it may be a jack-up barge provided with jack-up legs that may be located on the sea bottom and be used to stabilize the barge or lift the barge partially or completely out of the water.

In the first embodiment the supply vessel has the following main particulars:

Length overall 22.00 m Breadth 12.00 m Depth to upper deck  4.50 m Draught (free sailing)  2.00 m

The deadweight at summer draught may be at about 35 t.

The supply vessel has two hull sections 8 interconnected by a deck structure 22 and a deckhouse 9. The deckhouse has a lower part 21 with a passenger main saloon provided with a plurality of passenger chairs, such as 12 chairs. Next to the saloon the deckhouse has a lavatory, and the saloon may be provided with galley corner with dishwasher and cooking facilities. In an upper part 20 the deckhouse is provided with a bridge having at least a forward 18 and an aft 17 maneuvering position with skipper chairs, echo sounder, vhf radios and radar or other navigational and safety equipment.

In the bow the supply vessel is provided with a fender 16 at the middle of the bow. The aft deck has a tug layout. A towing winch 11 is located just aft of the deckhouse at a central location, and at the stern there is installed a stern roller 10 located also in a central location aft of the towing winch. In between the towing winch and the stern roller there is installed hydraulic pins 13. These pins can be hydraulically activated to move upwards to a position extending above deck level, or downwards to a retracted position with the top of pins flush with the deck surface. The pins are located on starboard and port side of the towing wire, or hawser, and restrict sideways movements of the towing wire during towing.

The aft deck is furthermore provided with a tugger winch 12 and with a deck crane 14. The tugger winch 12 helps the crew to operate heavy towing gears, like chains, chain bridles, towing plates, wires, and anchor handling. Hydraulic pins 13 can also be utilized to control a wire or hawser from the tugger winch. The deck crane is used e.g. for lifting supplies etc. onto or off the vessel. The tug layout of the aft deck provides a free area 19 aft of the towing winch 11, tugger winch 12 and deck crane 14. When towing, the free area 19 allows hawsers and wires to extend with an angle in relation to the longitudinal centre plane of the vessel. In order to exert a towing pull in a different direction, the vessel needs to be able to steer in a direction oriented towards the desired direction of pull, and in doing so the hawser or wire must be able to be angled with respect to the longitudinal centre plane of the vessel.

The free area in the aft part of the supply vessel brings an advantage to the transfer of service personnel. The free area allows the supply vessel to receive a personnel basket onto the deck in a safe manner. A personnel basket is a construction used to transfer personnel by hoisting. When personnel is to be transferred from the vessel to the offshore facility, the personnel basket is lowered down onto the free area by use of a crane and personnel to be transferred steps onto the basket, which then is hoisted and placed on the offshore facility. When personnel is to be transferred from the offshore facility to the vessel, the personnel basket with the personnel is lowered from the offshore facility down to the free area of the deck in the aft part of the supply vessel.

In front of the deckhouse there is a water tight locker bin 30. A propulsion engine is mounted in each hull portion in order to drive a propeller 31. A rudder 15 is located behind each propeller.

In the following description of a second embodiment of the supply vessel according to the present invention there is used the same reference numerals as in the above-mentioned description of the first embodiment of the supply vessel. And details already described with respect to the first embodiment, being likewise valid for the second embodiment, are not described in further detail, as general reference is made to the description of the first embodiment.

In the lower part 21 of the deckhouse a passenger saloon 20 is provided with a plurality of passenger chairs 21, such as 12 chairs. These chairs are used for the personnel being transferred by the supply vessel. Two lavatories 22 are arranged next to the saloon. A leisure area 23 with television or cinema facilities is also arranged in the saloon area. Next to the saloon there is a galley 24 with dishwasher and cooking facilities.

The free area 19 aft of the towing winch 11, tugger winch 12 and deck crane 14 is largely delimined by the lines marked B. The hydraulic pins 13 can be shifted down into a compartment 25 below deck so that the upper deck is mainly flush in the free area 19.

In order to facilitate transfer of personnel from the bow of the vessel to the offshore facility 1, the forward end of the vessel has a platform 26 on level with the top of fender 16, and stairs 27 up to the platform, and rails 28 on both lateral sides of the platform, so that personnel may safely walk from the deck of the vessel and up to platform 26 and onwards to enter the offshore facility 1.

In the second embodiment the supply vessel has the following main particulars:

Length overall 23 m Breadth 12 m Depth to upper deck 4.50 m Speed above 20 knots Bollard pull 25 t Towing winch 30 t Tugger winch 3 t Passengers 12 Crew 4 Propulsion engines 2 × 1100 hp

A propulsion engine 29 is arranged in each hull section 8, and via a propeller shaft 32 the propeller 31 is driven by the engine. The propeller may have adjustable pitch, and is located in a propeller nozzle 33. Each engine room is provided with ventilation air through air intakes 34 and 35. Each engine can deliver a power of 1100 hp.

The stern roller 10 located in a central location aft of the towing winch can be a fixed curved surface in the hull of the vessel, which curved surface allows the chains, wires or other equipment handled by the tugger winch and the towing winch to roll over and along the surface when entering or leaving the vessel. The stern roller can also be a circular cylindrical body mounted at the stern with a possibility to rotate about its central longitudinal axis. Next to and at a lower level than the stern roller the vessel has two platform areas 36 where crew can stand at a level closer to the sea level than when standing on the aft deck. Each hull section is provided with a cabin for crew in the area forward of the engine room.

The supply vessel may be embodied in other manners than described in the above, within the scope of the patent claims. For instance, the supply vessel can be provided with ballast tanks, such as ballast tanks located at or in the deck structure 22 interconnecting the two hull sections 8. By filling sea water into the ballst tanks, the total mass of the supply vessel becomes larger and this may cause the supply vessel to move more slowly or move less under the action of waves, which can be an advantage to the crew and to the operations performed by the crew. A larger mass of the supply vessel can also be an advantage when towing. During transfer at high speed these ballast tanks are empty in order to reduce the mass of the supply vessel. 

1. A supply vessel equipped with passenger seating for transferring service personnel to and from an offshore facility, said supply vessel having a transfer speed of at least 16 knots, wherein an aft deck of the supply vessel has a tug boat layout equipped with at least one towing winch, a stern roller, hydraulic pins and a tugger winch.
 2. A supply vessel as claimed in claim 1, wherein the supply vessel has a transfer speed of at least 18 knots.
 3. A supply vessel as claimed in claim 1, wherein the supply vessel has a transfer speed of at least 20 knots.
 4. A supply vessel as claimed in claim 1, wherein the supply vessel has a transfer speed of at least 24 knots.
 5. A supply vessel as claimed in claims 1, wherein the towing winch has at least one of a pulling capacity of at least 20 t, and a breaking capacity of at least 30 t.
 6. A supply vessel as claimed in claim 1, wherein the tugger winch has a pulling capacity of at least 2 t.
 7. A supply vessel as claimed in claim 1, wherein the aft deck is equipped with a crane capable of lifting at least 4 t.
 8. A supply vessel as claimed in claims 1, wherein the supply vessel has a deckhouse arranged with at least 5 passenger seats.
 9. A supply vessel as claimed in claims 1, wherein the supply vessel has a deckhouse arranged with at least 10 passenger seats.
 10. A supply vessel as claimed in claim 8, wherein the deckhouse has a bridge located in an upper part of the deckhouse, which bridge is arranged with an aft maneuvering position, and wherein the towing winch, the hydraulic pins and the tugger winch are controllable from the aft maneuvering position.
 11. A supply vessel as claimed in claim 1, wherein the supply vessel has two hull sections arranged in parallel and spaced apart by deck structure.
 12. A supply vessel as claimed in claim 1, wherein the supply vessel in its bow area has a fixed fender.
 13. A supply vessel equipped with passenger seating, said supply vessel having a transfer speed of at least 16 knots, wherein an aft deck of the supply vessel has a tug boat layout equipped at least with one towing winch, a tugger winch, and a free area aft of the towing winch and the tugger winch, said free area allowing reception of a personnel basket with personnel on the aft deck.
 14. A supply vessel as claimed in claim 13, wherein the supply vessel has a transfer speed of at least 20 knots.
 15. A supply vessel as claimed in claim 13, wherein the deckhouse has a bridge located in an upper part of the deckhouse, which bridge is arranged with an aft maneuvering position, and wherein the towing winch and the tugger winch are controllable from the aft maneuvering position.
 16. A supply vessel as claimed in claim 13, wherein the supply vessel in its bow area has a fixed fender.
 17. A supply vessel equipped with passenger seating, said supply vessel having a transfer speed of at least 20 knots, wherein an aft deck of the supply vessel has a tug boat layout equipped at least with one towing winch, a tugger winch, and a free area aft of the towing winch and the tugger winch, said free area having a size to receive a personnel basket with personnel on the aft deck.
 18. A supply vessel as claimed in claim 17, wherein the deckhouse has a bridge located in an upper part of the deckhouse, which bridge is arranged with an aft maneuvering position, and wherein the towing winch and the tugger winch are controllable from the aft maneuvering position.
 19. A supply vessel as claimed in claim 18, wherein the towing winch has a pulling capacity of at least 20 t. 